Application of Dynamic Hysteresis Band Height Control to Improve Output Voltage Transient in Boost and Positive Buck-Boost Converters

This paper presents dynamic hysteresis band height control to reduce the overshoot and undershoot issue on output voltage caused by load change. The converters in this study are Boost and Positive Buck-Boost (PBB) converters. PBB has been controlled to work in a step up conversion and avoid overshoot when load is changed. Simulation and experimental results have been presented to verify the proposed method.

Synthesis, Structure and Optical Studies of a Family of Three-Dimensional Rare-Earth Aminoisophthalates M(mu(2)-OH)(C8H5NO4)] (M = Y3+, La3+, Pr3+, Nd3+, Sm3+, Eu3+, Gd3+, Dy3+, and Er3+)

A hydrothermal reaction of the acetate salts of the rare-earths, 5-aminoisophthalic acid (H(2)AIP), and NaOH at 150 degrees C for 3 days gave rise to a new family of three-dimensional rare-earth aminoisophthalates, M(mu(2)-OH)(C8H5NO4)] M = Y3+ (I), La3+ (II), Pr3+ (III), Nd3+ (IV), Sm3+ (V), Eu3+ (VI), Gd3+ (VII), Dy3+ (VIII), and Er3+ (IX)]. The structures contain M-O(H)-M chains connected by AIP anions. The AIP ions are connected to five metal centers and each metal center is connected with five AIP anions giving rise to a unique (5,5) net. To the best of our knowledge, this is the first observation of a (5,5) net in metal-organic frameworks that involve rare-earth elements. The doping of Eu3+/(3+) ions in place of Y3+/ La3+ in the parent structures gave rise to characteristic metal-centered emission (red = Eu3+, green = Tb3+). Life-time studies indicated that the excited emission states in the case of Eu3+ (4 mol-% doped) are in the range 0.287-0.490 ms and for Tb3+ (4 mol-% doped) are in the range of 1.265-1.702 ms. The Nd3+-containing compound exhibits up-conversion behavior based on two-photon absorption when excited using lambda = 580 nm.

Rare-earth carboxylates, Ln(2)(III)(mu(3)-OH)(C4H4O5)(2)(C4H2O4)]center dot 2H(2)O Ln = Ce, Pr and Nd]: synthesis, structure and properties

A new series of inorganic-organic hybrid framework compounds, Ln(2)(mu(3)-OH)(C4H4O5)(2)(C4H2O4)]center dot 2H(2)O, (Ln = Ce, Pr and Nd), have been prepared employing a hydrothermal method. Malic acid and fumaric acid form part of the structure. The malate units connect the lanthanide centers forming Ln-O-Ln two-dimensional layers, which are cross-linked by the fumarate units forming the three-dimensional structure. Extra framework water molecules form a dimer and occupy the channels. The water molecules can be reversibly adsorbed. The dehydrated structure did not show any differences in framework structure/ connectivity. The presence of lattice water provides a pathway for proton conductivity. Optical studies suggest an up-conversion behavior involving more than one photon for a neodymium compound.

一种新的芴类衍生物的三光子吸收诱导荧光和光限幅效应研究

通过对新合成的芴的一种具有对称性衍生物4-2-（7-（4-氨基苯乙烯基）-9，9-二（2-乙基己基）-9H-芴-2-）乙烯基）苯胺（BASF）的DMF溶液的研究，发现其具有很强三光子吸收频率上转换荧光发射特性，实验测出上转换荧光的波长范围是456-775nm，在510nm处的荧光强度与入射光强的三次方成正比．在0．03mol／L的浓度下就有明显的三光子吸收诱导的光限幅效应．非线性吸收系数和吸收截面分别为y=4．34×10^20 cm^3／W^2和σ3=2．4×10^-39 cm^6／W^2．

Infrared-to-visible upconversion emissions in Er3+ doped TeO2-based oxyhalide glasses

The fluorescence and up-conversion spectral properties of Er3+-doped TeO2-ZnO and TeO2-ZnO-PbCl2 glasses suitable for developing optical fiber amplifier and laser have been fabricate and characterized. Strong green (around 527-550 nm) and red (around 661 nm) up-conversion emissions under 977 nm laser diode excitation were investigated, corresponding to H-2(11/2), S-4(3/2), --> I-4(15/2) and F-4(9/2) --> I-4(15/2) transitions of Er3+ ions respectively, have been observed and the involved mechanisms have been explained. The dependence of up-converted fluorescence intensity versus laser power confirm that two-photons contribute to up-conversion of the green-red emissions. The novelty of this kind of optical material has been its ability in resisting devitrification, and its promising optical properties strongly encourage for their further development as the rare-earth doped optical fiber amplifiers and upconversion fiber laser systems.

Structural role of fluoride in aluminophosphate sol-gel glasses: High-resolution double-resonance NMR studies

The local structure of Na-Al-P-O-F glasses, prepared by a novel sol-gel route, was extensively investigated by advanced solid-state NMR techniques. Al-21{F-19} rotational echo double resonance (REDOR) results indicate that the F incorporated into aluminophosphate glass is preferentially bonded to octahedral Al units and results in a significant increase in the concentration of six-coordinated aluminum. The extent of Al-F and Al-O-P connectivities are quantified consistently by analyzing Al-27{P-31} and Al-21{F-19} REDOR NMR data. Two distinct types of fluorine species were identified and characterized by various F-19{Al-27}, F-19{Na-23}, and F-19{P-31} double resonance experiments, which were able to support peak assignments to bridging (Al-F-Al, -140 ppm) and terminal (Al-F, -170 ppm) units. On the basis of the detailed quantitative dipole-dipole coupling information obtained, a comprehensive structural model for these glasses is presented, detailing the structural speciation as a function of composition.

稀土离子掺杂的多组分玻璃光纤

abstract {Rare earth ions doped multi-component glass fibers have important application in broad band fiber amplifier and up-conversion fiber lasers. In this paper, the mechanism and the progress of study on rare earth ions doped multi-component glass fibers in broad band fiber amplifier and up-conversion fiber lasers are introduced and reviewed. The questions and the applications of rare earth ions doped multi-component glass fibers in the future are also prospected. Based on the present research progress, it is suggested to further study the tellurite and bismuth glasses, which are used as fiber materials in broad band fiber amplifier. To up-conversion fiber laser, it is still need to further investigate novel glasses, which has low phonon energy and good physical and chemical properties.}

Er3+离子浓度对Er3+/Yb3+共掺磷酸盐玻璃上转换 发光的影响

The upconversion emission of Er³⁺/Yb³⁺ codoped phosphate glass with 980 nm excitation was investigated. In the glass Er³⁺ concentration has a great influence on the intensity and the ratio of green and red light upconversion. The slope of the green luminenscence intensity as a function of pumping power ranges from 2.52 to 3.27, is the evidence of the three photon excitation process. The three photon process can also be concluded from excitation spectra when emission wavelength is 545 nm. The effect of Er³⁺ concentration is also discussed.

掺铒磷酸盐玻璃波导放大器的特性研究

研究了掺铒磷酸盐玻璃波导放大器的特性。利用重叠因子将980nm光抽运的掺铒玻璃波导放大器四能级模型的速率-传输方程进行化简，在考虑上转换效应和放大自发发射的情况下．利用数值模拟的方法，得到了掺铒玻璃波导放大器的增益与Er^3+离子浓度、抽运功率、波导长度等参量之间的关系曲线；同时模拟出放大自发发射曲线并与实验测量结果进行比较。结果表明在考虑上转换效应和放大自发发射的情况下,理论结果和实验测量结果是一致的。同时看到，选择合适的铒离子浓度是制作掺铒玻璃波导放大器的关键；并且为了全面发挥掺铒玻璃波导放大器的性能

Spectroscopic properties of Er3+ doped TeO2-BaO (Li2O, Na2O)-La2O3 glasses for 1.5-mu m optical amplifiers

This paper reports on the optical spectroscopic properties and thermal stability of Er3+-doped TeO2-BaO (Li2O,NaO)-La2O3 glasses for developing 1.5-mu m fiber amplifiers. Upon excitation at 977 nm laser diode, an intense 1.53-mu m infrared fluorescence has been observed with a broad full width at half maximum (FWHM) of about 60 nm for the Er3+-doped TeO2-BaO (Li2O, Na2O)-La2O3 glass with 10 mol% of BaO. The calculated fluorescence lifetime and the emission cross-sections of the 1.53-mu m transition are 2.91 ms and similar to 9.97 x 10(-21) cm(2), respectively. It is noted that the gain bandwidth, a, x FWHM, of the TeO2-BaO-La2O3Er2O3 glass is about 600, which is significantly higher than that in silicate and phosphate glasses. Meanwhile, it is interesting to note that the TeO2-BaO-La2O3-Er2O3 glass has shown a high glass thermal stability and good infrared transmittance. As a result, TeO2-BaO (Li2O, Na2O)-La2O3 glass with 10 mol% of BaO has been considered to be more useful as a host for broadband optical fiber amplifier. (c) 2005 Elsevier B.V. All rights reserved.

Yb：YAG晶体的合作发光现象

研究了Yb：YAG晶体的合作发光现象。当用940hm的近红外光激发时，Yb：YAG晶体有明显的上转换蓝色发光。实验发现498nm的蓝色发光强度与激发功率的平方成正比，而且Yb^3＋掺杂浓度越高，蓝色发光越强。分析表明这是Yb^3＋间强的相互作用导致的合作发光，是由于Yb^3＋在共价性的YAG基质中，它的4f^I3电子易于与近邻离子发生相互作用导致的。

Room temperature efficient actively Q-switched Ho:YAP laser

We report on efficient actively Q-switched Ho: YAP laser double-pass pumped by a 1.91-mu m laser. At room temperature, when the incident pump power was 20.9 W, a maximum average output power of 10.9W at 2118 nm was obtained at the repetition rate of 10 kHz, and this corresponds to a conversion efficiency of 52.2% and a slope efficiency of 63.5%. Moreover, a maximum pulse energy of similar to 1.1 mJ and a minimum pulse width of 31 ns were achieved, with the peak power of 35.5 kW. (C) 2009 Optical Society of America

The wideband high-linearity mixers for cable television tuner application

The wideband high-linearity mixers for a double conversion cable TV tuner is presented. The up-conversion mixer converts the input signal from 100MHz to 1000 MHz to the intermediate frequency (IF) of I GHz above. And the down-conversion mixer converts the frequency back. The degeneration resistors are used to Improve the linearity. The tuner is implemented in a 0.35 mu m SiGe technology. Input power at 1dB compression point can reach +14.23dBm. The lowest noise figure is 17.5dB. The two mixers consume 103mW under a supply voltage of 5 V.

Two-dimensional beta-NaLuF4 hexagonal microplates

A simple hydrothermal method has been developed to synthesize monodisperse beta-NaLuF4 microplates in a large scale. The microcrystals have a perfect hexagonal shape with a diameter of about 5.2 mu m and a thickness of 300 nm. Trisodium citrate (Cit(3-)), which is introduced into the reaction mixture and acts as the chelating agent and shape modifier, plays a key role in fine-tuning the microstructures. The dominant adsorption of Cit(3-) onto the {0001} facets lowers the surface energy of these facets.

Sonochemical synthesis of monodispersed KY3F10 : Eu3+ nanospheres with bimodal size distribution

Monodispersed KY3F10:Eu3+ nanospheres with bimodal size distribution have been successfully synthesized via a facile and efficient sonochemical method in a surfactant-free system. Rare-earth nitrate (Y, Eu)(NO3)(3) and potassium fluoborate (KBF4) were used as precursors. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), and photoluminescence (PL) spectra were used to characterize the samples.